1. Field of the Invention
The field of the invention is the use of cyclopropanecarboxylates for systemic control of ectoparasites on animals.
2. The Prior Art
Ixodidae, or hard ticks, are generally categorized as one-host, two-host or three-host ticks. They sustain themselves and their species by attaching to a host animal and feeding on the blood and bodyfluids thereof. Engorged females drop from the host animal and lay their eggs (2,000 to 20,000) in a niche on the ground or in some sheltered area where hatching occurs. The larvae then seek a host from which to obtain a blood meal and depending on whether the tick is a one, two or three-host tick may drop off the host to molt.
Ixodid ticks are responsible for the transmission and propagation of a great many human and animal diseases throughout the world. Those ticks of major economic importance include Boophilus spp., Rhipicephalus spp, Ixodes spp, Hyalomma spp., Amblyomma spp., and Dermacentor spp. They are vectors for disease, tick paralysis and tick toxicosis. A single tick species can cause paralysis of several different mammals, and several tick species can cause paralysis in a particular host. Tick-borne diseases, such as Sweating Sickness, Babesiosis, Anaplasmosis, Theileriosis and Heartwater, have been and are responsible for the death and/or debilitation of a vast number of animals throughout the world each year. Ticks are responsible for great economic losses in livestock production in the world today. Such losses are, of course, attributable not only to death, but also to damaged hides, loss in growth rate, reduction in milk production and reduced grade of meat animals.
Although the debilitating effects of tick and other pest infestation of animals has been recognized for years, and tremendous strides have been made in tick control programs, no entirely satisfactory method for controlling or eradicating these parasites has been forthcoming. Topical treatment of tick-infested and other ectoparasite plagued animals with chemical ectoparasiticidal agents, such as the chlorinated hydrocarbons, including benzene hexachloride (BHC), DDT, toxaphene, chlordane and aldrin; the organophosphorus compounds, including Delnav, ethion and coumaphos, have been partially successful in controlling ectoparasite populations. However, certain species of ectoparasites have become resistant to the chlorinated hydrocarbons and the organophosphates.
Netherlands Pat. No. 7,307,130, issued Nov. 27, 1973, describes a broad class of cyclopropanecarboxylic acid ester derivatives which include the compounds I have found to be effective against ectoparasites. U.S. Pat. 3,835,176 (1974) teaches .alpha.-cyanobenzyl cyclopropenecarboxylates. The patentees do not, of course, suggest the systemic method of the present invention.